The causes of the heavy rainfall in Zhejiang induced by Typhoon Gaemi in 2024 are analyzed using ERA5 data, S-band dual-polarization Doppler weather radar data, X-band dual-polarization phased array weather radar data and observations of dense automatic weather stations. The results are listed as follows. (1) During the influence of Typhoon Gaemi, torrential rain is concentrated along the southeastern coast of Zhejiang with significant accumulated rainfall, and extreme rainstorms are recorded in southern Wenzhou. (2) Abundant moisture and energy are provided to Typhoon Gaemi by the southwest monsoon and the southeast jet on the western flank of the subtropical high, and the mountainous terrain significantly enhances the precipitation. (3) The S-band dual-polarization radar is distinguished by its long detection range and high data reliability in regions of strong echoes. In contrast, the X-band phased array radar with superior spatiotemporal resolution, can effectively capture the characteristics of low-elevation dual-polarization parameters during precipitation events, significantly enhancing observing capabilities in low-level blind zones. Additionally, the X-band radar’s dual-polarization parameters are higher overall, but exhibit a certain attenuation phenomenon after strong echoes. (4) The quantitative precipitation estimation (QPE) products derived from both the X-band radar network and the S-band radar are characterized by strong capabilities in representing heavy precipitation. However, the relatively limited number of heavy precipitation samples may result in significant fluctuations in the QPE evaluation metrics. The X-band radar has the advantage of high resolution in capturing localized intense rainfall, whereas the S-band radar can detect the precipitation over a broader area. Nonetheless, the ability to estimate the heavy precipitation exceeding 40 mm·h^-1 is relatively weaker for the S-band radar. (5) The precipitation locations and intensities are well estimated by the QPE from the X-band radar network, and the probabilities of detection (PODs) for various rainfall intensities are higher than those achieved by the S-band radar. From 02:00 BJT to 05:00 BJT 26 July, the average POD for heavy rainfall in Taizhou reaches 88%, representing an improvement of 63% compared to the S-band radar; however, the false alarm rate and bias are also noticeably higher.